In a mobile communication system, a third generation mobile phone system utilizing a CDMA (Code Division Multiple Access) system is currently put to practical use and a study of a next generation mobile communication system enabling faster communications to be performed has been recently studied (refer to Non-Patent document 1 given below). As to the next generation mobile communication system, an application of an OFDM (Orthogonal Frequency Division Multiplexing) system is examined in place of the CDMA system. The OFDM system is a technique of segmenting transmission data into plural pieces of transmission data, then mapping the segmented pieces of transmission data to a plurality of orthogonal carrier waves (subcarriers) and transmitting the data in parallel on a frequency-axis.
In the mobile communication system utilizing this type of OFDM system, the base stations neighboring to each other need allocating frequency bands different from each other. This is because if the neighboring base stations perform the wireless communications in a way that uses the same frequency band, mutual interference might be caused. It is, however, desirable for increasing the frequency utilization efficiency to enable, if practicable, the same frequency band to be used in the respective base stations.
In this respect, there is proposed a method of making a frequency repetitive distance variable corresponding to a distance of the mobile station from the base station (refer to Non-Patent document 2 given below). The frequency repetitive distance connotes a necessary distance (cell count) when considering an arrangement of the base stations (cells) in which the neighboring base stations do not use the same frequency band. According to this system, the interference with the neighboring base station is prevented by increasing the frequency repetitive distance (the frequency repetitive distance is set to, e.g., “3”) if the mobile station exists in a position remote from the base station, and the frequency utilization efficiency is improved by decreasing the frequency repetitive distance (the frequency repetitive distance is set to, e.g., “1”, i.e., all of the frequency channels can be used) if in a position close to the base station.
Non-Patent document 1: Technical Specification Group Radio Access Network, “Requirements for Evolved UTRA (E-UTRA) and Evolved UTRAN (E-UTRAN) (Release 7)”, 3rd Generation Partnership Project, 3GPP TR 25.913 V7.2.0, December 2005
Non-Patent document 2: Samsung, “Flexible Fractional Frequency Reuse Appro”, 3rd Generation Partnership Project TSG-RAN WG1, R1-051341, 8.2, November 2005